Re: '59 QD-20 only running on 1 cylinder

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Posted by Ed Mc. ( on July 11, 2005 at 12:17:46:

In Reply to: '59 QD-20 only running on 1 cylinder posted by Paul on July 11, 2005 at 11:44:43:

You can run the motor in a barrel then put a timing light on the #1 cyl to see if it's actually firing while running. It may have enough spark to fire a spark plug laid on the block, but may not be strong enough to fire in the cylinder.

Likely it's an old coil which failed after heating up. You can get new coils for good prices at

If when you open it up, you find any cracks or material oozing out of the other coil, it's bad too and should be replaced.

Can't recall, but your motor may have an access plate or hole where you can see the ign parts without pulling the flywheel.

Otherwise, to get the flywheel off you'll need an automotive-type harmonic balancer puller, and (3) Grade 8 or better puller bolts, sized 1/4-20 by about 3-1/2" or so.

While you're at it, pick up a Tune-up Kit and renew the points/condensers. It'll assure your Twin keeps purring for a long time. Adjust the points gaps to a "loose" .020" for better running.

Now, if you do find that you have a good, hot spark to the top cyl, pull the spark plug after running and make sure you see no water on the plug, which might indicate a leaking head gasket. Just a thought, since it was running good for a while I'd expect it's an ign problem.

HTH & G'luck........ed

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